Interstitial Oxygen Determination in Heavily Doped Silicon with "Peak-height" Method by FT-IR Spectra

Due to ineffectiveness of routine IR-absorption method for determinahon of intershtial oxygen in heavily doped silicon, a 'peak-height' method has been dcveloped. The phosphorus-doped CZ-Si with n=(7.l～l2)× 10~17cm^(-3) was taken as sample for characterization. The calculation results at 300 K and 10 K were ptesented in detail. The'peak-height' method is much simpler than 'short-baseline' and 'curved-baseline' methods.

The effects of interstitial oxygen on superconducting electronic phases in strontium and oxygen co-doped La_(1.937) Sr_(0.063) CuO_(4+δ)

Strontium and oxygen co-doped La1.937Sr0.063CuO4＋δ superconductor with Tc≈ 40K, which is obtained by oxidizing strontium-doped starting ceramic sample La1.937Sr0.063CuO4 in NaC10 solution, is annealed under different conditions to allow interstitial oxygen to redistribute. The evolution of the intrinsic superconducting property with the oxygen redistribution is studied in detail by magnetic measurements in various fields. It is found that there occurs the electronic phase separation from the single superconducting phase with Tc ≈ 40 K into two coexisting superconducting states with values of Tc： 15 and 40K or of 15 and 35 K in this system, depending on annealing condition. Our results indicate that the 15, 35 and 40 K superconducting phases associated with the excess oxygen redistribution are all thermodynamically meta-stable intrinsic states in this Sr/O co-doped cuprate.

Dimers as Fast Diffusing Species for the Aggregation of Oxygen in Boron-Doped Czochralski Silicon: Formation of New Thermal Donors

The thermal behaviors of oxygen-related complexes in boron doped Czochralski Silicon (Cz-Si) wafers at 450°C and 800°C were investigated using Fourier transform infrared spectroscopy (FTIR) and Hall mobility measurements. Activation of thermal donors (TDs) at 450°C leads to a decrease of both mobility and majority carrier concentration using the four point probes configuration of Van Der Pauw. It was found that annealing at 450°C would possibly affect the electronic properties of the Si wafers via the formation of interstitial dioxygen defects (IO2i), which exhibit an IR absorption band positioned at 545 cm–1. A strengthening of the IR bands peaking at around 1595 cm–1, 1667 cm–1, 1720 cm–1 and 1765 cm–1 occurs at 450°C, while they disappear at 800°C. At high temperatures, the precipitation of interstitial oxygen becomes predominant over all other oxygen-related reactions. The dynamic of oxygen-thermal donor generation-annihilation in Cz-Si involving the formation of small oxygen clusters is discussed.

Synthesis and Conductivity of Oxyapatite Ionic Conductor La10-xVx（SiO4）6O3＋x

Apatite-lanthanum silicate has attracted considerable interest in recent years due to its high oxide ion conductivity.In this paper,V-doped samples La10-xVx(SiO4) 6O3+x(0≤x≤1.5) were prepared by sol-gel method and the influences of V-dopant content on calcining temperature and conductivity were reported.The samples were characterized by thermal analysis(TG-DSC) ,X-ray diffraction(XRD) and scanning electron micrograph(SEM) . The apatite was obtained at 800°C,a relatively low temperature in comparison to 1500°C with the conventional solid-state method.The ceramic pellets sintered at 1200°C for 5 h showed a higher relative density than La9.33Si6O26 pellets sintered at 1400°C for 20 h.The conductivities of samples were measured by electrochemical impedance spectroscopy.The conductivity was improved with the increase of V-dopant content on La site.

Pressure-induced structural evolution of apatite-type La_(9.33)Si_6O_(26)

The pressure-induced structural evolution of apatite-type La9.33Si6026 was systematically studied using in situ syn- chrotron x-ray diffraction （XRD）. The XRD spectra indicated that a subtly reversible phase transition from P63/m to P63 symmetry occurred at ~ 13.6 GPa because of the tilting of the SiO4 tetrahedra under compression. Furthermore, the La9.33Si6026 exhibited a higher axial compression ratio for the a-axis than the c-axis, owing to the different axial arrange- ment of the SiO4 tetrahedra. Interestingly, the high-pressure phase showed compressibility unusually higher than that of the initial phase, suggesting that the low P63 symmetry provided more degrees of freedom. Moreover, the La9.33Si6026 exhibited a lower phase transition pressure （PT） and a higher lattice compression than LaloSi6027. Comparisons between La9.33Si6026 and LaloSi6027 provided a deeper understanding of the effect of interstitial oxygen atoms on the structural evolution of apatite-type lanthanum silicates （ATLSs）.

Synthesis and Conducting Properties of La10-x（SiO4）6O3-1.5x

The synthesis of silicate oxyapatitesLa10-x（SiO4）6O3-1.5x（x=0. 0.17, 0.33, 0.50 and 0.67） via a sol-gel method at 800 ℃ was reported. The apatite phases were characterized by X-ray diffraction （XRD） and conducting properties were studied by electrochemical impedance spectroscopy （EIS）. It is found that the conductivities are influenced by the amount of cation vacancies and interstitial oxygen. The conductivity of La9.33 （SiO4）6O2 with more cation vacancies is higher than that of La9.5 （SiO4）6O2.25. The conductivity of La10 （SiO4）6O3 with more interstitial oxygen is 7.98 ×10^-3 S·cm^-1, which is about 5 times higher than that of La9.33（SiO4）6O2 at 700℃. The electrical conductivity is almost independent of the oxygen partial pressure from 105 to 1 Pa, which suggests that the oxyapatites exhibit almost pure O^2- ion conduction over a wide range of oxygen partial pressure.